CN107445321A - Double-micro treatment process for treating oilfield produced water - Google Patents

Abstract

The invention relates to a double micro-treatment process for treating oilfield produced water. It mainly solves the problem that the existing treatment process that has been able to meet the water quality control index requirements of oilfield low-permeability reservoir reinjection water is relatively complicated and the treatment water quality cannot meet the standard stably. It is characterized in that it includes the following steps: (1) the oil-containing produced water enters the micro-swirl air flotation device for oil-water separation; (2) the effluent treated by the micro-swirl air flotation device enters the buffer tank 1 and the micro-filtration device, and the micro-swirl air flotation device The effluent from the filter device enters the external water transfer tank after meeting the water quality control index requirements of oilfield reinjection water; (3) The water in the external water transfer tank is lifted to backwash and regenerate the filter material in the micro-filtration device after one filtration cycle; (4 ) The backwash sewage discharged from the micro-filtration device enters the buffer tank 2 and the micro-swirl air flotation device for further treatment. The process can meet the water quality control index requirements of reinjection water in low-permeability or ultra-low-permeability reservoirs in oilfields.

Description

A double micro-treatment process for treating oilfield produced water

technical field

The invention relates to the technical field of oilfield produced water treatment, in particular to a double micro-treatment process for treating oilfield produced water.

Background technique

At present, the existing oilfield produced water treatment technology adopts gravity settling tank or air flotation to remove oil and remove part of suspended solids, and the effluent meets the influent water quality required by subsequent filtration; then it is filtered through granular filter material filter to reach Reinjection water quality control indicators for different permeability reservoirs required by oilfields. At present, the most typical treatment technology that the final effluent after treatment can meet the water quality control index requirements of low permeability or ultra-low permeability oil layer reinjection water is: gravity settling tank→air flotation→microorganism→first-stage double-layer Filter material filtration→secondary double-layer filter material filtration→ceramic membrane fine filtration→water purification.

Overall, the treatment process of this process technology is relatively complicated, and it needs to go through 6 stages of treatment equipment to treat the oily sewage up to the standard, that is, to meet the water quality control index requirements of oilfield low permeability or ultra-low permeability oil layer reinjection water. The resulting large area, high operating costs, the residual activated sludge produced by the microbial treatment is difficult to meet the requirements of environmental protection, and the flux of the ceramic membrane decays quickly after a long period of operation, and Membrane regeneration also requires regular chemical regeneration to increase treatment equipment and complex processes, and the acid-base waste liquid generated during the regeneration process will be recycled in the system, which will affect the water quality of the entire system.

In addition, the treatment efficiency of the vertical settling tank used in the above-mentioned treatment process is relatively low compared with the high-efficiency treatment equipment, and the equipment volume is large and the floor area is large; there is also a chemical oil displacement agent in the water in the late stage of oilfield development, which makes the oily oil after oil-water separation Due to the high degree of emulsification of the produced water, the small size of the oil beads and the slow rise of the oil beads, it is difficult to achieve the expected effect and purpose by using a single physical method to achieve the oil-water sedimentation and separation of the produced oily sewage, which leads to the failure of the treatment equipment. Not suitable, resulting in complicated treatment process and increased engineering investment; in terms of filtration, single-layer quartz sand filters and double-layer filter media filters are mainly used, and walnut shells and fiber ball filter media are currently used in water flooding treatment. However, there are also problems such as inadaptability to changes in the properties of produced water containing chemical oil displacement agents, easy compaction of filter media, difficult regeneration and low filtration rate.

Contents of the invention

The present invention aims to overcome the existing problems in the background technology that can meet the water quality control index requirements of low-permeability reservoir reinjection water in the oil field, the processing technology is relatively complicated, and the water quality cannot be stably up to the standard, and provides a method for A dual micro-treatment process for treating oilfield produced water. The oilfield produced water treated by this process can meet the water quality control index requirements of oilfield low permeability or ultra-low permeability oil layer reinjection water, and under the premise of achieving the same treatment effect, the treatment equipment and process technology are advanced, the floor area is small, and the operation low cost.

The present invention solves its problem and can reach through following technical scheme: a kind of double micro-processing technique for processing oilfield produced water comprises the following steps:

(1) The oil-containing produced water to be treated is lifted by gravity or a booster pump into the micro-swirl air flotation device for oil-water separation to remove dispersed oil, partially emulsified oil and a small amount of particulate impurities;

(2) The effluent treated by the micro-swirl air flotation device enters the buffer tank 1, and the water in the buffer tank 1 enters the micro-filtration device through the lift pump 1, and the treated produced water completes conditioning and reaction in the micro-filtration device. And the process of filtration; the effluent of the microfiltration device reaches the water quality control index requirements of low permeability or ultra-low permeability oil layer reinjection water in the oil field, enters the external water transfer tank, and then enters the water injection station through the lift pump 3 for reinjection;

(3) Step (2) The water in the external water transfer tank is lifted by the lifting pump 4 to backwash and regenerate the filter material filled in the microfiltration tank after completing a filtration cycle, so that the filter material can restore the original interception and adsorption capacity, and then proceed to the next filtering cycle;

(4) Step (3) The backwash sewage discharged from the backwash regeneration of the filter material filled in the microfiltration tank enters the buffer tank 2, and then is lifted by the lifting pump 5 to enter the water inlet pipeline of the microcyclone air flotation device, and enters the microcyclone Flow air flotation device for reprocessing;

(5) Step (1) The scum produced by the oil-water separation of the micro-swirl air flotation device enters the scum tank, and then is lifted by the pump into the dehydration station for dehydration and reprocessing; After the sludge is discharged into the sludge tank, it is concentrated, and then the sludge treatment station for further treatment is carried out to achieve harmless and resourceful utilization;

The treatment process of "micro-swirl air flotation → micro-filtration device → purified water" determined by the present invention, firstly, the oily produced water enters the micro-swirl air flotation device, and the micro-swirl air flotation device integrates micro-swirl technology and air flotation technology High-efficiency treatment device; when the device is in operation, the oily produced water to be treated is firstly lifted by gravity or a booster pump, passes through the pipeline static mixer (mainly considering the mixing effect of the chemical agent and sewage during dosing), and then passes through the micro-swirl air The water inlet line of the flotation device is mixed with the micro-bubble water generated by the micro-bubble generating device at the same time, and enters the micro-swirl air flotation device along the tangential direction, and the oil droplets and impurities are removed under the compound action of the swirl centrifugal force + air flotation buoyancy. Aggregation and adhesion (microbubble water releases microbubbles to adhere to oil droplets and suspended solids under the condition of reduced pressure), so as to quickly and efficiently realize centrifugal flotation separation to remove oil and remove suspended solid impurities.

The microfiltration device is composed of a buffer conditioning device, a reaction device and a microfiltration tank, wherein the microfiltration medium adopts active microporous ceramic coating filter material for filtration treatment. The active microporous ceramic coating filter material has a large specific surface area and the ability to efficiently absorb impurities in sewage, coupled with the use of a deeper filter bed form, so that the microfiltration has a higher dirt-holding capacity and a higher Filtration accuracy; in addition, due to the use of pulse gas and water combined backwashing to regenerate the active microporous ceramic coating filter material, it has the characteristics of good regeneration effect and saving a lot of backwashing water.

Compared with the above-mentioned background technology, the present invention can have the following beneficial effects: adopting the double micro-treatment process for treating oilfield produced water of the present invention greatly simplifies the existing treatment process flow on the one hand and improves the treatment effect of the overall treatment process and efficiency; on the other hand, because the micro-swirl air flotation device is used for oil-water separation to replace the two-stage sedimentation oil removal equipment, the effective residence time of the treated sewage is shortened, and the dispersed oil and part of the emulsified oil in the sewage can also be removed. It greatly saves more than 50% of the equipment's floor area and reduces operating costs; the subsequent filtration method for removing residual oil and residual solid particle impurities can finally reduce the oil content to an average of 147.7mg/L, The treated produced water with an average suspended solid content of 35.07mg/L, the oil content of the effluent water after treatment is traces, the average suspended solid content is ≤1.0mg/L, and the average median particle size is 0.946μm, reaching the oilfield ultra-low permeability oil layer "5.1 .1” (ie: oil content ≤ 5mg/L, suspended solids content ≤ 1mg/L, particle size median ≤ 1μm) water quality control index requirements for reinjection water, the present invention uses microfiltration technology, compared with existing sand filtration Filtration technology improves the filtration accuracy by 1 to 2 orders of magnitude (the filtration accuracy of general sand filtration is about 2-5 μm, while the filtration accuracy of microfiltration can reach below 1 μm); in addition, it also solves the problem of using ultrafiltration membrane modules. Short, fast decay of water flux, difficult membrane regeneration and other practical problems in production. Therefore, the use of micro-swirl air flotation and micro-filtration technology can meet the effective development of extra-low permeability oil layers in peripheral oilfields, ensure that all the treated oily sewage is re-injected underground, further oil displacement improves oil recovery, and realizes the recovery of sewage. Resource utilization and green development of oil fields.

Attached to the manual:

Accompanying drawing 1 is a schematic flow chart of the double micro-treatment process for treating oilfield produced water according to the present invention.

detailed description:

The present invention will be further described below in conjunction with accompanying drawing and specific embodiment:

As shown in Figure 1, the double micro-treatment process for treating oilfield produced water includes the following steps:

(1) The treated oily produced water enters the micro-swirl air flotation unit by gravity (or booster pump lift) for oil-water separation to remove dispersed oil, partially emulsified oil and a small amount of particulate impurities. After entering the micro-swirl air flotation unit At the same time, flotation reagents and return water with micro-bubbles can be added to the water inlet pipeline, and then enter the micro-swirl air flotation unit together with the treated sewage;

(2) The effluent treated by the micro-swirl air flotation device enters the buffer tank 1, and the water in the buffer tank 1 enters the micro-filtration device through the lift pump 1; the micro-filtration device is composed of buffer conditioning, reaction device and micro-filtration Tank composition; the microfiltration medium filled in the microfiltration tank is filtered by active microporous ceramic coating filter material; while the active microporous ceramic coating filter material K80≤1.2, the specific surface area reaches 13.6m ² /g; microfiltration The thickness of the filter bed inside the tank reaches 3m, and the filtration accuracy of the microfiltration is below 1μm; the process of conditioning, reaction and filtration is completed in the microfiltration device, and the conditioning flocculant is added to the water inlet pipeline of the microfiltration device Polyaluminum chloride flocculates the impurity particles in the produced water to form larger flocculent alum flowers, which are absorbed and retained by the subsequent active ceramic filter material with deep bed filtration characteristics, and the effluent of the microfiltration device reaches the quality of oilfield reinjection water After the control index is required, it enters the external water transfer tank, and then enters the water injection station through the lift pump 3 for reinjection;

(3) The water in the external water transfer tank is lifted by the lift pump 4 to backwash and regenerate the filter material filled in the microfiltration tank in the microfiltration device after one filtration cycle, so that the filter material can restore its original interception and adsorption capacity. Filtration in the next filtration cycle; in the process of backwash regeneration of the filter material, it is necessary to mix the gas generated by the air compressor into the backwash to form gas-water backwash water, thereby improving the regeneration effect of the filter material in the microfiltration tank ;

(4) The backwash sewage discharged from the backwash regeneration of the microfiltration tank in the microfiltration device enters the buffer tank 2, and then is lifted by the lifting pump 5 into the inlet pipeline of the microcyclone air flotation device, and then enters the microcyclone air flotation device for further processing. Reprocessing;

(5) The scum produced by the oil-water separation of the micro-swirl air flotation device enters the scum tank, and then is lifted by the pump into the dehydration station for dehydration and reprocessing; the sludge separated from the bottom of the micro-swirl air flotation device is discharged into the The sludge is concentrated after the sludge tank, and then transported to the sludge treatment station for further harmless treatment and resource utilization.

The microfiltration device is composed of buffer conditioning, reaction device and microfiltration tank, and the microfiltration medium adopts active microporous ceramic coating filter material for filtration treatment. The active microporous ceramic coating filter material has a larger specific surface area (the active microporous ceramic coating filter material is a uniform filter material that is artificially fired, K80≤1.2, and the specific surface area reaches 13.6m ² /g, which is 100 times that of quartz sand. times, greatly improving its surface adsorption capacity) and the ability to efficiently adsorb impurities in sewage, plus the deep filter bed form inside the filter tank (the thickness of the filter bed reaches 3m, which is the thickness of the walnut shell and quartz sand filter bed 3 times that of quartz sand, and the actual effective filtration range is more than 5 times that of quartz sand, which improves the filtration effect), so that microfiltration has high dirt holding capacity and high filtration accuracy (generally, the filtration accuracy of sand filter is about 2-5μm, The filtration accuracy of microfiltration can reach below 1μm); in addition, because the pulse gas and water combined backwashing are used to regenerate the active microporous ceramic coating filter material, it has the characteristics of good regeneration effect and saving a lot of backwashing water. Subsequent filtration method for removing residual oil and residual solid particle impurities can finally reduce the treated produced water with an average oil content of 147.7mg/L and an average suspended solid content of 35.07mg/L, and the oil content of the treated effluent For traces, the average suspended solid content is ≤1.0mg/L, and the average particle size is 0.946μm. , median particle size ≤ 1μm) Reinjection water quality control index requirements.

The water quality treated by the micro-filtration device can finally meet the water quality control index requirements of oilfield water flooding low permeability or ultra-low permeability oil layer reinjection water, and then reinjection underground through water injection wells to supplement the formation deficit and achieve the purpose of oil displacement and enhanced recovery , avoid environmental pollution and economic fines caused by sewage discharge, realize effective treatment of oily sewage and resource utilization of sewage, ensure that all treated sewage is reinjected into the ground, further increase crude oil recovery, and realize green development of oil fields.

Claims (7)

1. a kind of double microprocessor techniques for being used to handle oil field extracted water, comprise the following steps：

（1）Processed oil-containing recovered water is lifted into micro- cyclone gas floatation device by gravity or booster pump and carries out water-oil separating Except dispersed oil and part oil emulsion and a small amount of granule foreign；

（2）Water outlet after the processing of micro- cyclone gas floatation device enters back into surge tank 1, and the boosted pump 1 of water of surge tank 1 enters in a subtle way Filter, the quenched and process of reaction and filtering is successively completed in microfilter device；The water outlet of microfilter device reaches oil field Enter outer water delivery tank after low-permeability or the requirement of Extra-low permeability oil reservoir reinjected water Water Quality Control Indexes, then boosted pump 3 enters Water-injection station carries out re-injection；

（3）Step（2）The boosted pump 4 of water in outer water delivery tank is lifted to enter the filtrate in microfilter device after a filter cycle Row backwash regeneration, make the filtering that filtrate recovers original retention and adsorption capacity carries out next filter cycle；

（4）Step（2）The backwashing sewage water of microfilter device discharge enters surge tank 2, then boosted pump 5 is lifted into micro- eddy flow In the back with water inlet line of gas floatation device, enter cyclone air-flotation in a subtle way and select device to be reprocessed；

（5）Step（1）Oil slick slag caused by micro- cyclone gas floatation device progress water-oil separating enters oil slick slag ladle, is then lifted through pump Dehydration reprocessing is carried out into dehydrating plant；The sludge that micro- cyclone gas floatation device bottom sedimentation separation comes out is carried out after being discharged into sludge tank Concentration, then outward transport Treatment of Sludge station, which does further to handle, reaches innoxious and recycling.

A kind of 2. double microprocessor techniques for being used to handle oil field extracted water according to claim 1, it is characterised in that：Entering Enter step（1）The backflow of floating agent and incorporation with microbubble can be added in the back with water inlet line of micro- cyclone gas floatation device simultaneously Water, together enter cyclone air-flotation in a subtle way with processed sewage and select device.

A kind of 3. double microprocessor techniques for being used to handle oil field extracted water according to claim 1, it is characterised in that：Entering Enter step（2）Quenched flocculant is added in the back with water inlet line of microfilter device, make the impurity particle in recovered water flocculate to be formed compared with Big cotton-shaped alumen ustum, removed so as to be retained by the active ceramic filtrate with deep-bed filtration feature.

A kind of 4. double microprocessor techniques for being used to handle oil field extracted water according to claim 1, it is characterised in that：Step （3）In the backwash regenerative process for carrying out filtrate, gas caused by air compressor machine is incorporated into backwash and forms air water back washing Wash water.

A kind of 5. double microprocessor techniques for being used to handle oil field extracted water according to claim 1, it is characterised in that：Step （3）Microfilter device is formed by buffering quenched, reaction unit and micro-filtration tank.

A kind of 6. double microprocessor techniques for being used to handle oil field extracted water according to claim 3, it is characterised in that：It is described The microfiltration media loaded in micro-filtration tank carries out filtration treatment using active micropore ceramic coating filtrate；And active micropore ceramic coating Filtrate K80≤1.2, specific surface area reach 13.6m²/g；Filter bed thickness reaches 3m inside micro-filtration tank, and the filtering accuracy of micro-filtration is 1 μ Below m.

A kind of 7. double microprocessor techniques for being used to handle oil field extracted water according to claim 3, it is characterised in that：It is described Quenched flocculant is aluminium polychloride.